Piston ring



y 30, 1933- F w. WXLKENlNG 1,911,736

PISTON RING Filed Feb. 16, 1951 16$ 57/ 1 J ll l l W 18 1 32 1 %A j m mmINVENTOR.

1% EedericK h/ilKeniy Patented May 30, 193 3 UNITED STATES PATENT OFFICEFREDERICK W. WILKENING, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TOWILKENING MANUFACTURING COMPANY, OF PHILADELPHIA, PENNSYLVANIA, A.

CORPORATION OF DELAWARE PISTON RING Application filed February 16, 1931.Serial no. 516,130.

The present invention relates generally to a class of piston ringscommonly referred to as oil-control rings, and it relates more par:ticularly to a novel oil-controlring construction, whereby certaindeficiencies and undesirable characteristics of the prior oil-controlrings may be entirely eliminated, and whereby a much improved productmay be obtained.-

Amohg the several practices followed heretofore in making oil-controlrings, various types of openings have been employed to V convey the oilthrough the ring to the space between the ring and the back of the ringgroove, and thence through holes drilled 1n the piston to the crankcase.Also various means have been employed to secure an effective contactbetween the outer periphery of the ring and the cylinder wall. No adequate provision has been made to prevent the passage of oilfrom thespace in back of the ring, to the cylinder wall above the ring throughthe clearance between the side or face of the ring and the side-wallring groove.

Thus, even with adequate drainage through the ring and effective contactwith the cylinder wall, it has not been possible to prevent efieetivelythe passage of oil around the ring and thence to the head of the piston.

To eliminate these deficiencies and overcome these undesirablecharacteristics inherent in the prior oil-control ring constructions,my'present invention contemplates a certain radially perforated andexternally. double channeled ring whereby a substantially uniformoutward radial pressure may be obtained, producing a complete uniformityof contact between the entire outer periphery of the ring and thecylinder under all conditions, and whereby the desired oil drainagethrough the radial perforations of the ring may bemaintained, andwhereby also an effective contact may be obtained between the side faceof the ring and the side-wall of the the piston into the combustionchamber at the same time permitting a proper and suflicient lubricationof the cylinder walland minimizing the frictional resistance and weardue to the 'rings- With the foregoing and other objects in v1ew, myinvention consists of and includes certain features of constructionwhich will appear more fully from the following detailed description.

For the purpose of illustrating my inven tion I have shown in. theaccompanying drawing one form thereof which is'at present pre-- ferredby me, since the same has been found in practice to give "satisfactoryand reliable results, although it is to be understood that.

the various instrumentalities of which my invention consists can bevariously arranged and organized and that my invention is not limited tothe precise arrangement and organization of the instrumentalities asherein shown and described.

Referring to the drawing in which like ref- I erence characters indicatelike parts Figure 1 represents a fragmentary sectional view of a pistoncontaining a piston ring of the present invention, in relation to thecylinder walls, shown on a much'enlarged scale.

Figure 2 represents a top plan view of the same shown in relation to thepiston.

' Figure 3 represents a perspective view of an expander spring adaptedto'form part of my novel ring construction.

The ring 11 of the novel construction of the instant invention is of thesplit cast iron type, to be mounted in the conventional ring groove 21in which a series of radial oil drain holes or apertures 24 areprovided, intermediatethe bottom' of the ring groove 21 and the interiorof'the piston. Outward radial tension is preferably built into the ring,so

that the ring becomes self-expanding.

A double channel 12 is provided in the outer face of the ring 11,preferably spaced equidistantly from the two plane parallel faces 15 and16' thereof, so as to provide a pair of outer .annular bearing surfaces17 and 18 respectively, onthe outer periphery of the ring,;o fapproximately equal width. The

double channel 12 is composed of an outer substantially rectangularportion '13 and an inner portion 14-preferably of semicircular.

or other curved cross-section; the diameter or maximum width of saidnner channel portion 14 being less than the width of thereotangularchannel portion 13 of the said double channel 12; thereby providing anouter rectangular channel and an inner curved channel. 1 e

The axial width of theouter rectangular channel 13 is so proportionedwith respect to the width of the ring, thatit will occupy approximatelytwo-thirds, more or less, of the width of the ring, thereby providingannular bearing surfaces 17 and '18, each approximately one-sixth, moreor less, of the Width of'the ring.

A series of apertures 19, preferably in. the formof generally radialcircular openings, are provided through the ring'from the inner circularchannel 14 to the inner diameter 20 ofthe ring.- The radial apertures 19may be of any suitable number and are preferably equidistantly spacedwith respect to each other, and are preferably of a diametersubstantially equal to, or slightly greater than, the maximum axialwidth of the inner channel' 14 andslightly less than the axial width oftheouter channel 13.

The radial width of the upper plane sideface 15, of the ring 11, whichcontacts with the corresponding side wall of the ring groove, is reducedto approximately onefourth the total radial width ofthe ring by anysuitable means, preferably by providing a slight bevel 30 at an angle ofapproximately five degrees, more or less, with the lane of the ring.This, while not apprecia ly'nor materially decreasing the width of theupper annular bearing or cylinder. contact surface 17, does materiallyreduce the upper efi'ective contact face or side of the ring which isjuxtaposed to the corresponding side wall of the ring groove 21. I

Toaugment or replace the outer radial pressure inherent in the body ofthe ring, aflat steel spring ribbon expander 25 is provided, beingsuitably corrugated in a radial direction to provide alternate inner andouter contact points 26 and 27, respectively, for engagement with thebottom of thering groove and the inner diameter of the ring respectively;preferably having its inner contact points 26 suitably weakened ornarrowed as indicated particularly in Figures 1 and 3. The radialexpander spring 25 is interposed between the bottom of the ring oove 21and the inner diameter of the ring. One of the advantages of my presentnovel ring construction is inproviding the necessary drainage throughthe ring in the form of a comparativelylarge number of comparativelysmall circular apertures, equidistantly spaced, which weaken thecross-section of the ring to a minimum extent for a given aggregatecross sectional area of apertures, and which, by dividing thecircumference of the ring into comparatively very short alternateperforated and non-perforated sections, -per mits the tension inherentin the ring to be distributed substantially uniformly through thecircumference of the ring.

By reason also of the inner channel 14, an increased effectiveness inthe drainage of oil through the ring is obtained, because said innerchannel 14 tends effectively to guide the oil film to the radialapertures 19.

Because the area of the upper side contact surface 15 of the ring hasbeen considerably reduced, by the slight beveling 30, the pressure perunit of area exerted between the upper side face 15 and thecorresponding side wall of the ring groove, on the down stroke of thepiston, is considerably increased. The effect of this increased unitpressure is to enable the comparatively narrow contact surface 15 toeffectively cut through the fihn of oil between the ring and the side ofthe ring groove and approach a perfect metal to metal contact betweenthe side face of the ring and the side wall of the ring groove, thuseffectively preventing the passage of oil from the space in back of thering to the cylinder wall above-the ring and thence to the head of thepiston.

In certain instances the axial width of the ring is preferably made fromthree to seventhousandths of an inch less than the width of the rooveinto which said ring is intended to be pdaced, thereby creating aclearance space 31 between the side wall of the ring and the lower sidewalls of the ring groove.

The action of the. ring is as follows:

Because the area of the outer peripheral cylindrical contact face of thering has been considerably reduced by the double channel 12, thecomparatively narrow annular contact surfaces 17 and 18 of the ring areurged into contact with the cylinder wall with a greater pressure perunit of contact area, and tend to break through the oil film adhering tothe cylinder surface, and to ride back and forth over a comparativelythinner oil film, than what would obtain were the contact surface of thering equal to the entire width of the ring. This causes some of the oilfilm to be scraped onto the'side walls of the outer channel 13 duringthe successive strokes of the piston. The oilfilm thus gathered on thewalls of the outer channel 13 then passes onto the curved walls of theinner channel 14, from whence it is effectively drained through theradial apertures 19. The oil is thus gathered behind the ring and isthen drained back into the crankcase through the drain apertures 24extending through the piston wall. On the downward stroke of the pistonthe ring will be forced upwardly in the groove by the frictional drag ofthe cylinder wall upon the ring, and because of the much increasedpressure per unit area between the upper contact face 15 of the ring andthe corresponding side wall of the ring groove, the film of oil adheringto the side surface of the ring and the side wall of the ring groove isefiectively cut, effectively preventing the passage of any oil orcompressed gases between these surfaces.

For fitting cylinders which may be worn and somewhat out of round, andin general for use as replacement. rings, 'my novel piston ring may bemade without any or with lessened outward radial tensionin the body ofthe ring, that is, with the ring normally in a generally collapsedcondition, and the radial width of the ring may be decreasedsufficiently to provide a somewhat pliable ring body which may then beexpanded outwardly by the radial expander spring 25 as shownparticularly in the drawing. In this form of my novel ring construction,the ring may be caused to follow any slight irre larities in thecylinder wall, by reason of lts somewhat pliant and lifeless conditionand by reason of the uniformly distributed outward radial pressureexerted upon the ring by the expander spring 25 bearing against it 'at aseries of uniformly spaced points.

In this form of my present invention, the comparatively narrow bearingsurfaces 17 and 18 may be urged into contact with the cylinder wall withsubstantially uniform pressure of suflicient degree to cause an eflec-'tive gathering of the oil into the channel 13 and a drainage of the oilfrom the walls ofsaid channel and from the walls of the inner channel 14through the small radial openings 19, the high unit pressure between theupper side surface 15 and the corresponding side wall of the grooveeffectively preventing the passage of oil between thesesurfaces.

I am aware that my invention maybe embodied in other specific formswithout departing from the spirit or essential attributes thereof, and Itherefore-desire the present embodiments to be considered in allrespects as illustrative and not restrictive, reference being hadto theappended claims rather than to the foregoing description to indicate thescope of the invention.

Having thus described 111 invention, what I hereby claim as new andesire to secure by Letters Patent, is:

1. In. combination with a. cylinder and a piston adapted. forreciprocation therein and having an annular, parallel walled ringreceiving groove, of a split metallic piston ring operatively disposedwithin said ring receiving groove, said piston ring'having a pair ofspaced parallel outer cylindrical surfaces for contacting engagementwith the cylinder wall and having an annular channel intermediate saidpair of'outer contact faces, said annular channel having a pair of planeand parallel outermost side-walls and an inner wall portion of curvedcross-section intermediate said outermost and parallel side-walls andspaced from said side-walls 'by corresponding connecting wall portionsintermediate said plane parallel outermost side-walls and said innerwall of curved cross-section, said connecting wall portions extendlngtransversely of sa1d outermost side-walls, and a series of comparativelysmall round holes extending from said inner annular channel through saidring, and a series of holes extending from the bottom of thering groovethrough the wall of the piston ;one of the side-contact surfaces of saidpiston ring having an area substantially less than the area of the otherside-contact ceiving groove, said piston ring having a pair I of spacedparallel outer cylindrical surfaces for contacting engagementwith thecylinder wall and having an annular channel intermediatesaid pair ofouter contact faces, said annular channel having a pair of plane andparallel outermost side-walls and an inner portion of curvedcross-section intermediate said outermost and parallel side-walls,- andspaced from said side-walls by corresponding connecting wall portionsintermediate said plane parallel outermost side walls and said innerwall of curved cross-section, said connecting wall portions extendingtransversely. of said outermost side-wall, and a series of comparativelysmall round holes extending from said inner annular channel through saidring, and a series of holes extending from the bottom of the ring groovethrough the wall of the piston, and means intermediate the inner wall ofthe ring-receiving groove and the piston ring for exerting a generallyuniformly distributed outward radial pressure upon said ring whereby thetwo annular cylindrical contact surfaces of the piston ring are urgedinto contact with the cylinder wall and are caused to follow any slightirregularities of the same one of the side-contact surfacesof saidpiston ring having an area substantially less than the area of the otherside-contact surface thereof. 1 J

3. In combination with a cylinder anda pistdn adapted for reciprocationtherein and having an annular, parallel walled ring receiving groove, ofa split metallic piston ring operatively disposed within said ringreceiving groove, said piston ring having a pair of spaced paralleloutercylindrical surfaces for contacting engagement withthe cylinderannular channel having a pair of plane and parallel outermost side-wallsand an inner wall portion of curved cross-section intermediate saidoutermost and parallel side-walls and spaced from said side-walls bycorresponding connecting wall portions intermediate said plane paralleloutermost side-walls and said inner wall of curved cross-section saidconnecting wall portions extending transversely of said outermostside-walls, and a series of comparatively small round holes extendingfrom said inner annular channel through said ring, and a series of holesextending from the bottom of the ring groove through the wall of thepiston ;the upper side-contact surface of said piston ring having anarea substantially less than the lower side-contact surface thereof.

4. In combination with a cylinder and a piston adapted for reciprocationtherein and having an annular, parallel walled ring receiving groove, ofa split metallic piston ring cooperatively disposed within said ringreceiving groove, said piston ring having a pair of spaced parallelouter cylindrical surfaces for contacting engagement with the cylinderwall and having an annular channel intermediate said pair of outercontact faces, said annular channel having a pair of plane and paralleloutermost side-walls and an inner portion of curved cross-sectionintermediate said outermost and parallel side-walls, and spaced fromsaid side-walls by corresponding connecting wall portions intermediatesaid plane parallel outermost side walls and said inner wall of curvedcross-section, said connecting wall portions extending transversely ofsaid outermost side-wall, and a series of comparatively small roundholes extending from said inner annular channel through said ring, and aseries of holes extending from the bottom of the ring groove through thewall of the piston, and means intermediate the inner wall of thering-receiving groove and the piston ring for exerting a generallyuniformly distributed outward radial pressure upon said ring whereby thetwo annular cylindrical contactsurfaces of the piston ring are urgedintocontact with the cylinder wall and are caused to follow any slightirregularities of the same ;--the upper side-contactsurface of saidpiston ring having an area substantially less than the lowerside-contact surface thereof.

In testimony whereof I have hereunto set 5 my hand this 26th day ofSept, 1930.

FREDERICK W. WILKENING.

